Switching power supplies utilize a plurality of switches which are turned on and off to switch an input DC voltage across a transformer to a load, the output voltage at a different DC voltage level. By switching the current inductively coupled through the transformer to the load in a particular manner, a DC output voltage at a different voltage level than the input DC voltage level can be provided to the load. The control of the switching is typically facilitated with some type of control circuit. This control circuit can be an analog control circuit formed from a plurality of analog discrete devices, or it can be a digital circuit.
In digital control circuits, Digital Signal Processors (DSPs) have been utilized. The DSPs control the duty cycle and relative timing of the switches such that the edges of each control pulse to the various transistor switches controlling power delivery to the load will be varied. In order to perform this operation in the digital domain, the DSP must perform a large number of calculations, which requires a fairly significant amount of code to be generated to support a specific power supply topology, operating frequency, component characteristics and performance requirements. For example, inductor size decreases with increasing PWM frequency: dead times increase with increasing transistor turn-off times, and so on. Although DSPs can handle the regulation tasks, they are fairly complex and expensive and code changes in power supply applications are difficult.